Adding static email () to mailscript (ticket system)

Hello, I am looking for someone who tells me where to insert a static email () to mailscript of a ticket system (osTicket). I already inserted and it worked using internal PHP mail() function for outgoing emails. But know I have to change settings in osTickets to use SMTP server for outgoing emails and I guess should be insertet at another place in the script. I guess for someone who understands php-language it should be easy. In the attachment you can see where I added and it works with "using internal PHP mail() function for outgoing emails" setting but not with "use SMTP server for outgoing emails" Thanks a lot and kind regards, Stefan